Liquid fuel pumping apparatus for supplying fuel to internal combustion engines



3,42 6,689 UEL M. DRORI LIQUID FUEL PUMPING APPARATUS FOR SUPPLYING F TOINTERNAL COMBUSTION ENGINES Feb. 11, 1969 Filed Feb. 16, 1967 Q mm mummm Ow United States Patent 8,589/ 66 US. Cl. 103-41 Int. Cl. F04d 15/00;F04b 13/00, 23/12 5 Claims ABSTRACT OF THE DISCLOSURE Fuel injectionapparatus of the rotary distributor type and incorporating a feed pumpwhich supplies fuel to the injection pump of the apparatus. The outputpressure of the feed pump being controlled by a valve member which ismovable under the action of centrifugal force to close a spill port fromthe outlet of the feed pump, and which is movable in the oppositedirection by a force developed by the output pressure of the feed pump.A pressurizing valve is provided downstream of the spill port to preventthe flow of fuel therethrough until the output pressure of the feed pumpattains a predetermined value.

This invention relates to liquid fuel pumping apparatus for supplyingfuel to internal combustion engines and of the kind comprising incombination, an injection pump which is adapted to be driven in timedrelationship with an engine with which the apparatus is associated, theinjection pump serving during a delivery stroke to cause fuel to bedelivered to the engine, a feed pump for supplying fuel to the injectionpump and a valve member the setting of which determines the area of aspill port by which means the output pressure of the feed pump iscontrolled, said valve member having a surface against which the outputpressure of the feed feed pump acts in opposition to centrifugal forceacting upon a mass which is adapted to be rotated in timed relationshipwith the engine whereby the output pressure of the feed pump iscontrolled in a manner so that it varies with the speed of the engine,the valve member also serving to control the flow of fuel from the feedpump to the injection pump so that in the event that the output pressureof the feed pump falls below a value determined by the speed at whichthe engine is operating the valve member will move to cut off the supplyof fuel to the injection pump.

Such an apparatus is described in Patent No. 3,289,590 of Hutcheon. Inthis specification the mass is urged by springs in a direction so thatwhen the apparatus is at rest the spill port is closed. In this mannerthe output pressure of the feed pump can build up quickly as the engineis started, unfortunately however the provision of the springs meansthat the supply of fuel to the injection pump is prevented valve member.If the springs are ommited then owing to the effect of gravity and thefact that at the normal cranking speed of the engine the centrifugalforce is small the valve member can oscillate between a position inwhich the flow of fuel to the injection pump is prevented and a positionin which the ice maximum spillage of fuel through the spill port occursthereby making it difficult to supply sufficient fuel to the engine forstarting purposes. Moreover the output pressure at cranking speeds wouldbe too small to fill the injection pump particularly if the plungerstherein stick.

The object of the present invention is to provide such an apparatus in aform in which the starting of the engine is facilitated.

According to the invention in an apparatus of the kind specifiedadditional valve means is provided to prevent the fiow of fuel throughsaid spill port until the output pressure of the feed pump attains apredetermined value.

According to a further feature of the invention damping means isprovided to reduce the amplitude of oscillation of the valve member.

One example of a pumping apparatus in accordance with the invention willnow be described with reference to the accompanying sectional sideelevation. The apparatus includes a body part 10 in which is mounted arotary distributor 11 which is arranged to be driven in timedrelationship with the engine 12 with which the apparatus is associated.At one end of the distributor a transverse bore 13 is provided in whichare mounted a pair of pumping plungers 14 which are arranged to be movedinwardly as the distributor rotates by a cam surface formed on theinternal periphery of an annular cam ring 15 mounted in the body part.Moreover, the distributor is provided with passages through which fueldisplaced from the transverse bore can flow in turn to outlet ports 16formed in the body part. The apparatus is also provided with anhydraulic governor 17 the setting of which is dependent upon the outletpressure of a feed pump and the governor spring loading. The governorcontrols the quantity of fuel which is admitted to the transverse bore13 during the permitted outward movement of the pumping plungers. Thisfuel is obtained from a feed pump but flows through a separate passageindicated at 18 on the accompanying drawing, the output pressure of thefeed pump controls the setting of the governor and this fuel is appliedto the governor through a passage such as is indicated at 19 in theaccompanying drawing. The portion of the apparatus so far describedoperates in a well known manner but for a better understanding referencecan be made to our copending application previously mentioned.

At the end of the distributor 11 remote from the transverse bore 13 ismounted the feed pump which includes a rotary part 20 formed as anextension of the distributor. The rotary part has mounted thereon fourvanes 21 which are radially disposed and equiangularly spaced relativeto the axis of rotation of the rotary part 20. Moreover, diametricallyopposite blades are interconnected by bridge portions 22. The vanes areaccommodated within the bore of a ring 23 and bear upon the internalperiphery thereof. The ring is secured within an extension of the bodypart and the bore thereof is eccentrically disposed relative to the axisof rotation of the rotary part. By this arrangement a vane pump isformed and which is provided with an inlet 24 and an outlet 25.

The outlet 25 of the feed pump discharges into an annular chamber 26defined in the body part by way of a plurality of holes 27 formed in adiifuser ring 28, the holes serving to even the flow of fuel into thechamber. The passage 19 extends from the chamber 26 and within thechamber rotates a mass in the form of a head 29 of a valve member 30which is mounted within a diametrical bore formed in the distributor.Near one end of the bore there is formed a circumferential groove 31which communicates with the passage 18. Moreover, near the opposite endof the bore is formed a passage which is tangential to the axis ofrotation of the distributor and which opens into the bore accommodatingthe valve member 30 at a pair of spill ports 32 only one of which isseen because of the section. The other end of this passage opens intothe chamber 26. Intermediate the ports 32 and the groove 31 the bore isenlarged and is in communication with a passage 33 extending through therotary part 20 and which communicates with an inlet chamber 34 to whichfuel can be supplied through an inlet port 37.

As shown in the drawing the valve member 30 is provided with two lands Aand B the diameter of land A being larger than the diameter of land B.When the valve member is moved outwardly due to the action ofcentrifugal force acting on the head 29, land B moves to reduce the areaof the ports 32 whilst land A will move to reduce the annular area ofthe circumferential groove 31 which is exposed to the bore. Also in usefuel pressure will act on the head 29 and valve member 30 but in view ofthe difference in diameter of the two lands the force produced by thefuel pressure will act in opposition to the centrifugal force. In use anequilibrium position will be attained in which the ports 32 arepartially closed and the groove 31 fully open so that fuel can flowwithout hindrance through the passage 18 to the injection pump.

When the flow of fuel from the chamber 26 to the injection pumpincreases or decreases without a variation in speed then the valvemember will move to effect com pensation and the result is that the fuelpressure will vary in accordance with the speed irrespective of thequantity of fuel supplied by the injection pump to the engine. In theevent that the fuel pressure in the chamber 26 falls below a valuedetermined by the speed at which the engine is operating due forinstance to a blocked inlet or air entering the inlet, the valve memberwill move outwardly under the action of centrifugal force and the flowof fuel through the passage 18 will be reduced or prevented. In thelatter case no more fuel will be supplied to the injection pump and theengine to which fuel is being supplied by the apparatus will stop.

This arrangement prevents engine run away which might otherwise occurwhen the pressure of fuel controlling the setting of the governor 17falls. The device operates very satisfactorily when the engine hasstarted and sufficient speed has been attained however, when startingthe engine, the effect of gravity particularly when the axis of thevalve member 30 is vertical, coupled with the fact that the centrifugalforce and the fuel pressure are very low permits the valve member tooscillate between its two extreme positions. In one of these positionsthe spill ports 32 are effectively fully open whilst in the otherposition the groove 31 is blocked off and the spill ports are closed. Insaid one position the build up of fuel pressure is very small whilst inthe other position no fuel can reach the injection pump.

In the apparatus described in the specification of Patent No. 3,289,590springs are provided to urge the valve member towards the position inwhich the spill ports are closed. The provision of the springs meansthat the output pressure/speed characteristic of the combination of feedpump and regulator valve which is a square low is altered. In thepresent apparatus springs are not provided to bias the valve memberinstead, a pressurizing valve is provided to enable the fuel pressure inthe chamber 26 to be built up quickly. The pressurizing valve includes avalve member 38 having an annular sealing lip which is adapted to sealagainst a sealing surface defined about the point of entry of thepassage 33 into the chamber 34. The valve member 38 is loaded by aspring 39 in a direction to seal the passage 33 and is supported by aflexible diaphragm 40 which also is perforated to define a fuel filterfor the fuel passing through the inlet 37. Conveniently the valve member38, the diaphragm 40 and a support ring surrounding the diaphragm areformed integrally from nylon or some other suitable material. By thismeans before fuel can be spilled through the spill ports 32 the pressurein the chamber 26 must have attained a pressure sufficient to overcomethe effect of the spring 39. In this manner sufficient output pressurewill be built up quickly to move the valve member (if necessary) andrapid starting of the engine will be achieved. The valve member 38 alsoincorporates a nonreturn valve 41 which when the apparatus is in use isclosed but which when the apparatus is primed by pumping fuel underpressure through the inlet port 37, opens to allow fuel to flow into theinterior passages of the apparatus.

In order to damp the oscillation of the valve member a dashpot isprovided this havin the form of a cup member 42 which is retainedrelative to the distributor 11 and into which the free end of the valvemember 30 extends in the manner of a loose fitting piston. The cupmember is provided with an aperture or apertures 43 by which means theinterior of the cup member is placed in restricted communication withthe chamber 26, and by this means the amplitude of oscillation of thevalve member which occurs as the distributor rotates is reduced. Thedamping effect of the dashpot must not be too high otherwise the valvemember will be unable to move quickly enough to perform its controlfunction outlined above.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid fuel pumping apparatus for supplying fuel to internalcombustion engines and comprising in combination, an injection pumpwhich is adapted to be driven in timed relationship with the engine withwhich the apparatus is associated, a feed pump for supplying fuel underpressure, conduit means through which fuel flows from the outlet of thefeed pump to the injection pump, a spill path from the outlet of thefeed pump, valve means for controlling the flow of fuel through saidspill path whereby the pressure at the outlet of the feed pump can becontrolled, a surface defined on said valve means, said surface beingexposed to the outlet pressure of the feed pump, the force developedacting to urge the valve means in one direction to permit a larger flowof fuel through the spill path, centrifugally operable means acting onthe valve means to urge the valve means in the opposite direction toreduce the flow of fuel through the spill path, said centrifugallyoperable means being driven in timed relationship with the apparatus,and a valve mounted in said spill path and operable to prevent the flowof fuel through the spill path irrespective of the setting of said valvemeans, until the outlet pressure of the feed pump has attained apredetermined value.

2. A liquid fuel pumping apparatus according to claim 1 in which saidvalve is positioned in the spill path downstream of the valve means.

3. A liquid fuel pumping apparatus according to claim 2 includingdashpot means operatively connected to said valve means for restrictingthe rate of movement thereof.

4. A liquid fuel pumping apparatus according to claim 3 includinghydraulic pressure operable governor means for controlling the flow offuel through said conduit means thereby to control the quantity of fueldelivered by the injection pump to the engine, the hydraulic pressurefor operating the governor means being obtained from the outlet of thefeed pump.

5. A liquid fuel pumping apparatus according to claim 4 in which saidvalve means additionally controls the flow of fuel through said conduitmeans, the valve means When the flow of fuel through the conduit means.

urged fully in said opposite direction serving to prevent 3,292,5463,351,020

References Cited 5 DONLEY J.

UNITED STATES PATENTS Hutcheon.

Glikin.

Evans et al 103-2 Kemp 103 2 10 6 12/1966 Hutcheon. 12/1966 Evans.11/1967 Kemp 103-2 STOCKING, Primary Examiner.

U.S. Cl. X.R.

